


Cold Recollection

by hyliank8



Category: Undertale (Video Game)
Genre: Angst, Betrayal, Brotherly Love, But also, Healthy Sanster, Hurt/Comfort, M/M, Night Terrors, Non-consensual Soul Touching - Freeform, PTSD, Panic Attack, Soul Abuse, Unethical Experimentation, Unhealthy Sanster, W. D. Gaster is not related to Skelebros, sort-of grief but Gaster's not really gone completely, unintentional self-harm
Language: English
Status: Completed
Published: 2020-04-25
Updated: 2020-04-25
Packaged: 2021-03-02 00:20:05
Rating: Mature
Warnings: Creator Chose Not To Use Archive Warnings, No Archive Warnings Apply
Chapters: 1
Words: 3,273
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/23842138
Author URL: https://archiveofourown.org/users/hyliank8/pseuds/hyliank8
Summary: Sans is no stranger to the pain or the nightmares, but that doesn't mean he's used to them.He wishes he could get through a night's sleep without being plagued by the past; but when has he ever gotten what he wants?
Relationships: Papyrus & Sans (Undertale), W. D. Gaster/Sans
Comments: 25
Kudos: 78





	Cold Recollection

**Author's Note:**

> (me sitting down to write this fic, cracking my knuckles): alright brain, you know the drill. time to Produce Angst™
> 
> i was tryna try some different style stuff this time and tbH i don't like this too much anymore bc i think i stared at it for too long but aNYWAYS eheheheee more angst and longest length fic 2 date bc it takes me Actually Forever 2 write, pls enjoy

It twists in his rib cage—cold, _freezing_ ice. He can’t think, can’t even breathe freely; it’s like inhaling needles, each heaving intake of air ceaselessly piercing the inside of his chest as though punishing him for his weakness. Tears stream down his face as he desperately tries to steady his breath, to hold back his sobs, to keep _quiet_ as he curls into himself atop his worn-down mattress. He reminds himself that Papyrus deserves to be able to sleep one night without his worthless brother keeping him up with his pathetic tears, but the fear crawling through him prevents his body from relaxing.

It had seemed so real; it always does. One moment he’d lay down to sleep and the next… the next—

 _Cold hands holding him down by the wrists. Their grip feels somewhat familiar—the shape of the hands, the perfectly circular scar he feels outlined in the center of both—but the malicious intent is foreign, so different from what he used to know. Something wraps around his soul, squeezing tight and he can’t feel anything else, can only feel the pain and the confusion and the betrayal and it hurts it hurts it_ _hurts — _

Pain throbs through his fragile soul. A whimper escapes him despite his best efforts, and then the noise draws out into a whine and a hiccup follows and before he can stop himself he’s sobbing into his sleeves all over again, bringing his knees closer to his chest in a pointless attempt to curl tighter into himself. 

~~_As if trying to hide ever protected him._ ~~

A visceral urge to shield his soul overwhelms him, regardless of the fact that he knows his soul is as safe as it possibly can be—in his rib cage where it always rests, covered by his shirt and his hoodie. It’s safe, it’s not bared to anyone, it’s okay, no one is trying to pin him down and tear it from him— 

He knows he felt awful the last time he woke Papyrus in the middle of the night with one of his pathetic episodes, so he works on taking in deep, full breaths like he’s practiced so many times before with his brother’s help. Fear still grips his soul tight and the air catches in his throat periodically, but he manages to slowly curtail the overwhelming panic into a more manageable, idle anxiety. The subdued unease is certainly familiar to him—and it’s comforting, almost, that he’s managed to stomp down his panic into the same degree of substantial dread that is ubiquitous to all other hours of his days.

He supposes he’s grateful at least that the dream ended before it could get as… _graphic_ , as what he’s grown to expect. Really, it’s _fine_ , he just needs to steady his breathing a bit better, stop his tears, stop being so pathetic, stop being so _worthless, why can’t he do anything right, just hold still while I_ —

He shudders. One night. That’s all he wants. He wishes the dreams would let him rest for _one_ night. 

God, he’s pathetic, he’s _pathetic_.

Eventually, he manages to slow his breathing enough for the exhaustion to return, and the world fades around him as sleep claims him once more.

—

_Sans’ shirt comes off and is thrown to the side. It doesn’t land—when it’s tossed it disappears, consumed by the endless darkness._

_“Huh.” Gaster studies him with that detached, curious look in his eyes as though he’s sizing Sans up, determining his usefulness like he’s a lab specimen._

_Sans feels distinctly_ small _beneath Gaster’s cold, calculating gaze. The culmination of his being glows weakly, the dull blue glint barely filtering through his rib cage and making no mark on the endless void that surrounds the two of them. The cool air bites at his bared soul, and his bones begin to rattle as the distinct knowledge of his vulnerability grips him like a vice._

 _Gaster’s face splits into a grin, and Sans’ soul runs cold in terror when black sludge drips from the space between his lover’s teeth, from his eyes, from the splits in his head. Gaster chuckles darkly, and a syringe appears in his scarred hand. His voice distorts as he speaks through the sludge. “_ ** _Y_** _o_ ~~ ** _u_**~~ ** _r_** ~~ ** _e_** _a_~~ _l_ ~~ _l_~~ _y_ ** _ar_** _e_ ~~ ** _n’t_**~~ ** _w_** ~~ _or_~~ _th m_ ** _u_** ~~ ** _ch_**~~ ** _, a_** _re_ _y_ ~~ _o_~~ ** _u_** _?”_

—

This time, he wakes up to the distant sound of someone screaming. 

The door to his room swings open and suddenly Papyrus is there, knelt beside him, his eye sockets wide with worry. Why does he look so scared? He’s saying something to Sans—or at least Sans _thinks_ he must be saying something because his jaw is moving, but he can’t hear any of the sounds that leave his mouth over the static blaring in his ears.

The static moves to his vision, too—it’s hard to see Papyrus’ face in front of him, hard to see _anything_ past the blotches of darkness in his sight.

He reassures Papyrus that he’s okay, he’s okay, he’s fine, there’s no need to worry, but he can’t hear the words leave his mouth and can’t feel his mouth moving and behind his brother the shadows in the room are crawling and they’re coming closer and closer and— 

~~_“You’re my favorite toy, Sans,” Gaster’s breath scorches the side of his skull. His voice is a whisper, but it rings in Sans’ ear canal like a blood curdling scream. “And you were never anything more than that.”_ ~~

~~_stop, stop, no, that can’t be right. he loved me, he used to love me, it was only after the DT that he—that_ can’t _be right, it can’t—!_~~

His soul is burning, there’s something wrong, something seriously wrong with his soul—there’s something foreign lurking at its core and it feels alien and _wrong_ and _not him_ and he needs to get it _out_ of him, it’s going to _kill_ him if he doesn’t get it out. Pain flares on the surface of his sternum, steadily increasing, sharpening as his panic rises.

“ _Sans!_ ” He finally hears his brother cry, though his voice is still muffled through the static. “Brother, stop it! _Stop!_ ”

Someone is trying to grab his wrists, and Sans _knows_ they’re going to hold him down and take his soul away from him and hurt him for their own curiosity and he can’t, he can’t take that again, he _can’t!_ He tries to lash out with blue magic to get the monster _away_ from him but his soul spasms painfully, far too unstable to cast his magic. And that makes everything so much _worse_ because he can’t even use his _magic_ _;_ he’s trapped. He’s _defenseless._

~~_He’s going to hurt him. Again._ ~~

“n-no!” Sans chokes out, continuing to try to keep his wrists away from his aggressor. And still there’s something _in his soul and he needs to get it out it’s not his it’s not him._ “d-don’t!” 

~~_Leather straps hold him to the cold metal examination table. He yanks on them desperately as Gaster approaches, a syringe filled with a red substance held in his scarred hand; no, stay back, stay back, ‘dings please if there’s any part of you left please don’t do this please—!_ ~~

“ _Brother!_ ” Papyrus’ cry rings even through the deafening static, desperate like Sans hasn’t heard in a long, long time. “It’s me! Stop it, you’re hurting yourself!”

The monster finally catches his wrists and keeps them trapped in front of him _no no no help me please no somebody anybody—_ and the monster doesn’t try to pin him down like he expects but it doesn’t matter, _it doesn’t matter_ because they’re still holding him captive, they’re still preventing him from getting away and getting _whatever_ is inside his soul _out_.

~~_“I’ve always wondered if it’s possible to exert influence over a living monster soul… what do you think, Sans? My research hasn’t led anywhere—there’s no documentation on such a topic… it seems this is an unexplored area of our field. Personally, I think it could be possible with the right intent, but there’s no way of knowing without experimentation…”_ ~~

~~_Sans can’t breathe._ ~~

~~_“...Well, we’ll just have to test my hypothesis, won’t we?”_ ~~

“ _Sans!_ ” Sans can _hear_ the tears in his voice, _feel_ the panic in his brother’s soul even over his own soul’s erratic pulsing—and that sparks a sudden desperation within him that forces some of the static away because _his little brother is in distress and he’s got to help him, he’s_ got _to_.

His vision clears enough for him to be able to see his hands, and his soul twists in horror when he realizes they’re covered in magic blood—oh stars, _no_ , did he hurt someone? Did he hurt Papyrus? The mental foothold Papyrus’ voice provided for him already begins to disintegrate and he finds himself slipping back into unreality, his thoughts spiraling into panic once more, _no, no, no, no—_

“Look at me!”

His voice cuts through Sans’ panic once more, powerfully this time. Sans blinks, noticing that the hands that hold his wrists are unscarred and skeletal, and he wrenches his eyes up from his own hands to meet his brother’s terrified eyes.

“It’s _me,_ brother,” Papyrus says as soon as their eyes meet. There are worried tears building in his eye sockets, and the sight makes Sans’ protective instincts curl unpleasantly in his soul. “I’m here. You are _safe_.”

Sans is silent for a moment, trembling in his brother’s hold, but eventually he forces his voice to work voluntarily. 

“...papy.” Saying the nickname grounds him further—it forces the blare of the static in his ears to soften further, the shadows in the room to retreat to their corners. His soul still reels painfully from the aftershocks of panic, but his brother’s gaze is an anchor that tethers him to reality. The grip Papyrus has on his wrists shifts from threatening to comforting, and as Sans focuses on the steady weight of his hands his terror melts away. His brother’s soul emanates a strong, protective aura, and simply being in its proximity slowly ebbs away the pain in his own soul.

“I am here, brother,” Papyrus repeats, keeping careful, calm eye contact. “I am here, and he cannot hurt you anymore, okay? You are safe and no one is ever going to hurt you like that ever again.”

“i-... i—” Emotions swirl in Sans’ soul, complicated and painful and _confusing as all hell_ . He _wants_ to believe Papyrus. He wants it to be okay now—he’s safe, nobody will hurt him, he’s here with Papyrus and he’s going to be okay—but it's _not_ okay.

Because his best friend is gone, and somewhere underneath all of that pain and fear and trauma he _misses_ him, too. The _real_ him, the one uncorrupted by the thirst for power the DT experiments left him with. 

The Gaster he spent hours with almost every night working overtime in the labs, the Gaster driven by integrity and perseverance. 

The Gaster who was his best friend, who encouraged him through his self-doubt, who was always there to listen to anything that was bothering him, always there to hold his hand. Who often joined him in hours’ worth over-caffeinated laughter over niche jokes about quantum physics that so few other monsters in the underground were capable of grasping in the first place.

The Gaster who looked upon him with such fondness, such _love_ in his eyes.

~~_Maybe that’s the worst part. That Sans still loves him. That Gaster is his best friend and his soulmate and that Sans knows he is, and that hasn’t changed just because Gaster’s changed. Sans still loves him._ ~~

Sans wants him back with _everything_ he has and he _knows_ it’s possible, _knows_ he could accomplish it if he was to fix Gaster’s machine. But the terror of uncertainty crawls beside his longing for his best friend—Gaster could easily be just as corrupted once he returns. And Sans—he can’t—he can’t think about that again, but—Gaster _did_ seem to experience a moment of… lucidity, before he fell.

~~_Sans knows him well enough to see the flicker of doubt behind the sadistic glint in his eyes._ ~~

Would that last if Sans brought him back now?

~~_Sans sees him standing at the edge of the walkway at the CORE, standing on the other side of the railing. His uneven foothold through the bars and grip on the railing is all that is keeping him from plummeting to meet his fate._ ~~

~~_Sans knows it’s not Gaster anymore, not really, but he calls out for him anyway with tears in his eyes, a hand desperately extended towards the empty shell of his best friend. He knows he’s too far away to reach him in time, with blue magic or otherwise._ ~~

~~_Gaster meets Sans’ gaze. The remorseful expression that crosses his face before he lets go of the railing is so daringly reminiscent of the monster he used to be._ ~~

Sans shivers harder from the memories. He shakes his head in attempt to clear his mind; it works well enough to bring him back to the present. Suddenly remembering what he saw earlier, Sans looks back down at his hands. He still sees blood on them—the red didn’t go away with the static and the crawling shadows.

“wh-what…?”

Papyrus’ expression eases from worry into something halfway between sympathetic and troubled. “You were clawing at yourself again,” Papyrus says gently, though Sans can tell by the uncharacteristic softness to his voice that he absolutely _was_ just as terrified as he looked earlier.

 _Clawing_ at himself? When did he—all he remembers is the pain in his soul and—

Oh. His sternum.

He looks down. His shirt is blotched with blood where he must have scratched open his bones in his desperate, mindless attempt to reach his soul. Even through the thin fabric, his pointed fingers had clearly dug in enough to leave a considerable wound.

“o-oh.” He distantly realizes how lucky he was that he lacked the true intent to harm himself—Papyrus could have walked into his room to find a pile of dust.

He tries not to think about that.

Papyrus regards him carefully. “It's… bleeding pretty badly, brother. Is it okay if I heal it for you?”

Sans nods. “y-yeah." He’s grateful there’s at least one person he knows he can always trust without second-guessing himself. "thanks, pap.” 

Papyrus nods and releases his wrists, his hands coming up to hover over Sans’ sternum. A green glow emanates from his hands, and Sans slowly feels the sharp pain on the surface of his sternum begin to melt away.

Papyrus drops his hands once the pain is finally gone. He looks as though he’s about to say something, but Sans doesn’t want to think about what caused the pain in the first place anymore, doesn’t want to perseverate on his damaged soul and _certainly_ does not want to talk about it, so he speaks up before Papyrus can start.

“i know this was a lot, but… c-can we, maybe uh. not talk about this right now?” _or ever_ , he wants to add, but he knows with Papyrus as his brother that that would be unrealistic. “i just… i already woke up once tonight from… one of these things, and i’m too exhausted to really think about anything.”

Papyrus’ brow furrows, likely in response to learning about the episode that Sans had suffered through silently, but he nods gently nevertheless.

“th-thanks, bro… uh… d-do you think… i mean, w-would it be alright if i slept in your room tonight?” He curses his inability to keep his voice from wavering. He can’t help but feel pathetic, like a five-year old who has to ask to sleep in his parents room because of the imaginary enemies in his closet.

But Papyrus only gives him his characteristic radiant smile, and Sans’ soul warms as though he’s on the surface standing under the Sun. “Of course, brother. But let’s get you into some fresh clothes first, okay?”

Sans agrees. He struggles to maneuver himself with his trembling, so Papyrus assists him by finding and helping him into a fresh shirt and fresh pair of shorts. When he’s dressed Papyrus picks him up effortlessly, and Sans buries his head comfortably into the crook of his brother’s neck as Papyrus carries him to his room.

When he gets to the edge of his race car bed, Papyrus pulls back the covers and gently deposits his smaller brother onto the fresh sheets. Sans relaxes almost immediately, decidedly comfortable knowing that he will not be left alone with his mind any longer tonight. Papyrus crawls into the bed next to him and pulls the covers over them both, taking an extra moment ensure that his brother is tucked in properly. The simple yet meaningful gesture warms Sans’ soul.

“any chance we could sleep in tomorrow?” Sans says, only half-joking. Papyrus gives a theatrical sigh. 

“Well, you know how I _loathe_ to miss even a second of my schedule, but… yes!” He smiles then, and Sans finds himself mirroring the expression automatically.

“Undyne cancelled our cooking lesson unexpectedly for a date she’s got tomorrow anyways, so I was going to clean up around here since _somebody_ around here has to counteract a certain short skeleton’s messy ways,” he emphasizes his words with mock indignation. Sans grins wider and can’t help but chuckle genuinely. 

“But! I _suppose_ I can cancel my very important cleaning time to spend some extra time with my dear brother, messy as he may be! Even if we will only be sleeping!”

“hey, that’d do ya some good, right paps? you gotta get more sleep anyhow.”

“Yes, yes, I suppose I could give into your lazy ways just this once,” he relents, and gives the top of Sans’ skull a quick clonk with his teeth in the skeleton equivalent of a forehead peck. “Goodnight, Sans.”

“’night, paps.”

—

_Sans feels comfortably warm and particularly cozy, snuggled up against his tall partner. The small cot is tucked away in the corner of Gaster’s admittedly large office—moving it in here was the only solution Sans could find to get the scientist to sleep, some days. The cot is surprisingly comfortable, but it’s not the furniture so much as it’s the company that makes Sans feel so at home. Sans feels his soul thrumming in sync with Gaster's, idly sharing a wavelength as they tune into one another’s contentment._

_Sans nuzzles his head a bit further into Gaster’s shoulder and hums happily._

_“you’re real comfy, ‘dings, you know that?”_

_Gaster smiles and takes Sans’ much smaller hand in his larger, scarred one._

_“Glad I’m useful for you as a pillow, at least,” he teases lightly. He idly caresses his thumb over the back of Sans hand. It feels really, really nice._

_“don’t know why either of us would be surprised, i think we both always knew you were a_ softie _.”_

 _Gaster chuckles at the light pun. “Indeed, and that’s lucky for you,” he says. “I’m sure you wear out your other pillows from all your napping. At least you know I’ll always be here for you to lean on.”_

_It’s said lightheartedly, but the meaning behind it is enough to make Sans smile. “mm, yeah? always?”_

_Gaster squeezes his hand, his voice holding a gentle sincerity. “Always.”_

—

Sans blearily opens his eyes the next morning, his memory a slate wiped clean of whatever he dreamt last. 

The pillow beneath his eye sockets is damp.

**Author's Note:**

> lemme kno what u thought!!! if u want!!! (pls)
> 
> find me on [tumblr](https://hyliantimelordin221b.tumblr.com/) orrrrr [twitter (nsfw)](https://twitter.com/K8Maybe) if u would like 2 come say hi (or follow and watch my shenanigans from a distance)


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